U.S. patent number 5,070,826 [Application Number 07/571,528] was granted by the patent office on 1991-12-10 for electromagnetic valve actuating system.
This patent grant is currently assigned to Isuzu Ceramics Research Institute Co., Ltd.. Invention is credited to Hideo Kawamura.
United States Patent |
5,070,826 |
Kawamura |
December 10, 1991 |
**Please see images for:
( Certificate of Correction ) ** |
Electromagnetic valve actuating system
Abstract
An electromagnetic valve actuating system opens and closes
intake and exhaust valves of an engine under electromagnetic forces
generated by an electromagnet. A reciprocally movable magnetic pole
(6) in the form of an amorphous magnetic body is wound as multiple
layers on an intake/exhaust valve (9). An upper fixed magnetic pole
(3a) confronts one end of the movable magnetic pole (4), and a
distal fixed magnetic pole (3c) confronts the other end of the
movable magnetic pole. When the intake/exhaust valve (9) is to be
driven in an opening direction, the movable magnetic pole (4) is
attracted by the upper fixed magnetic pole (3a). When the
intake/exhaust valve (9) is to be driven in a closing direction,
the movable magnetic pole (4) is attracted by the distal fixed
magnetic pole (3c). Since the movable magnetic pole (4) is light in
weight, forces required to open and close the valve may be small,
and the electromagnetic valve actuating system may be small in
size.
Inventors: |
Kawamura; Hideo (Koza,
JP) |
Assignee: |
Isuzu Ceramics Research Institute
Co., Ltd. (Fujisawa, JP)
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Family
ID: |
18283168 |
Appl.
No.: |
07/571,528 |
Filed: |
November 13, 1990 |
PCT
Filed: |
December 28, 1989 |
PCT No.: |
PCT/JP89/01336 |
371
Date: |
November 13, 1990 |
102(e)
Date: |
November 13, 1990 |
PCT
Pub. No.: |
WO90/07639 |
PCT
Pub. Date: |
July 12, 1990 |
Foreign Application Priority Data
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Dec 28, 1988 [JP] |
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63-334961 |
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Current U.S.
Class: |
123/90.11;
251/129.01 |
Current CPC
Class: |
F01L
9/20 (20210101); H01F 7/1607 (20130101) |
Current International
Class: |
F01L
9/04 (20060101); H01F 7/16 (20060101); H01F
7/08 (20060101); F01L 009/04 () |
Field of
Search: |
;123/90.11,90.15
;251/129.01,129.05,129.09 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0162312 |
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Sep 1984 |
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JP |
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0183805 |
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Sep 1984 |
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JP |
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Primary Examiner: Cross; E. Rollins
Assistant Examiner: Lo; Weilun
Attorney, Agent or Firm: Staas & Halsey
Claims
I claim:
1. An electromagnetic valve actuating system for opening and
closing intake and exhaust valves of an engine, comprising:
a movable magnetic pole composed of an amorphous magnetic body
wound as multiple layers and mounted for reciprocating movement on
a valve;
an upper fixed magnetic pole confronting one end of said movable
magnetic pole;
an intermediate fixed magnetic pole (3b) coupled to said upper
fixed magnetic pole and confronting a side of said movable magnetic
pole;
a distal fixed magnetic pole (5c) coupled to said intermediate
fixed magnetic pole and confronting the other end of said movable
magnetic pole;
an upper coil (5a) for generating a magnetic flux passing through
the upper fixed magnetic pole;
a lower coil (5b) for generating a magnetic flux passing through
said distal fixed magnetic pole; and
energization control means (12) for energizing said upper and lower
coils to open and close said valve.
2. An electromagnetic valve actuating system according to claim 1,
wherein said valve is made of ceramic.
3. An electromagnetic valve actuating system according to claim 1,
wherein said energization control means applies an attractive force
acting between said movable magnetic pole and said distal fixed
magnetic pole before said valve is seated, thereby lessening shocks
produced when the valve is seated.
4. An electromagnetic valve actuating system according to claim 1,
wherein the timing established by said energization control means
to open and close the valve is variable as the rotation speed of
the engine varies.
5. A valve control system in an engine, comprising:
electromagnets having coils;
a valve having a movable magnetic pole composed of an amorphous
magnetic body wound in multiple layers on said valve; and
control means for controlling movement of said valve by energizing
and deenergizing the coils of said electromagnets at timings
corresponding to a speed of the engine.
6. A valve control system according to claim 5, further comprising
speed detection means for detecting a speed of the engine, and
said control means comprising a control unit including an
input/output interface connected to said electromagnets and said
speed detection means, a storage means for storing a table of the
timings corresponding to different speeds of the engine, and a
processor calculating the timing based on the speed detected by
said detection means.
7. A valve control system according to claim 6, wherein said
electromagnets have upper and lower coils, and the valve is moved
by alternately energizing the upper and lower coils.
8. A valve control system according to claim 7, wherein said
electromagnets comprise upper, intermediate and lower magnetic
poles, and
wherein said valve is closed by energizing the upper coil and
creating a line of magnetic force from the upper magnetic pole
through the amorphous magnetic body of said valve to the
intermediate magnetic pole and back to the upper magnetic pole, and
said valve is opened by deenergizing the upper coil and energizing
the lower coil and creating a magnetic line of force from the lower
magnetic pole through the amorphous magnetic body of said valve to
the intermediate magnetic pole and back to the lower magnetic
pole.
9. A method of controlling a valve with an electromagnet in an
engine, comprising the steps of
(a) providing the valve with an amorphous magnetic body;
(b) detecting the speed of the engine;
(c) reading the speed of the engine into a computer; and
(d) energizing and deenergizing the electromagnet at timings
corresponding to the speed of the engine, to move the valve by
attracting and repelling the amorphous magnetic body, under control
of the computer.
10. A method according to claim 9, wherein said energizing and
deenergizing of the electromagnets in step (d) is performed at the
timings read by the computer from a preset speed/time table based
on this speed of the engine.
11. A method according to claim 10, wherein the electromagnets
include upper and lower coils and have upper, intermediate and
lower magnetic poles, and wherein step (d) further comprises the
steps of (d1) holding the valve closed by energizing the upper coil
and creating a magnetic line of force from the upper magnetic pole
through the amorphous magnetic body to the intermediate magnetic
pole and back to the upper magnetic pole, (d2) opening the valve by
deenergizing the upper coil and energizing the lower coil and
creating a magnetic line of force from the lower magnetic pole
through the amorphous magnetic body to the intermediate magnetic
pole and back to the lower magnetic pole, (d3) closing the valve by
performing step (d1), (d4) decelerating the valve before it is
closed by performing step (d2), and (d5) finally closing the valve
by performing step (d1).
12. A method according to claim 11, wherein steps (d1) through (d5)
are repeated with each full piston stroke of the engine.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic valve actuating
system for opening and closing intake and exhaust valves of an
engine under electromagnetic forces generated by an
electromagnet.
2. Description of the Related Art
Some conventional actuating systems for opening and closing intake
and exhaust valves include a single camshaft which has cams to
operate the intake and exhaust valves, the camshaft being disposed
above or laterally by an engine. The camshaft is operatively
connected to the crankshaft of the engine by a belt or the like, so
that the camshaft can rotate synchronously with the rotation of the
engine.
In other valve actuating systems, an intake camshaft having cams
for acting on intake valves and an exhaust camshaft having cams for
acting on exhaust valves are disposed above an engine. The intake
and exhaust valves are opened when the stem ends of the intake
valves are directly pushed by the cam surfaces of the intake
camshaft and the stem ends of the exhaust valves are directly
pushed by the cam surfaces of the exhaust camshaft.
However, the above conventional actuating systems for opening and
closing intake and exhaust valves have several disadvantages.
First, the conventional systems include camshafts and link
mechanisms added to the engine, which necessarily renders the
engine large in size.
Secondly, since the camshafts and the link mechanisms are driven by
the output shaft of the engine, the engine output power is partly
consumed by the frictional resistance produced when the camshafts
and the link mechanisms are driven by the engine. As a result, the
effective engine output power is reduced.
Finally, the timing with which the intake and exhaust valves are
opened and closed cannot be altered during operation of the engine,
but the valve opening and closing timing is preset such that the
engine operates with high efficiency when it rotates at a
predetermined speed. Therefore, the engine output power and
efficiency are lower when the engine rotates at a speed different
from the predetermined speed.
To solve the above problems, there have been proposed valve
actuating systems for opening and closing intake and exhaust valves
under electromagnetic forces from electromagnets, rather than with
camshafts, as disclosed in Japanese Laid-Open Patent Publications
Nos. 58-183805 and 61-76713.
However, with the electromagnets disclosed in the above two
publications, the mass of the intake and exhaust valves is
increased, and large electric energy must be supplied in order to
actuate the intake and exhaust valve under electromagnetic forces
produced by the electromagnets.
SUMMARY OF THE INVENTION
In view of the aforesaid problems, it is an object of the present
invention to provide an electromagnetic valve actuating system in
which a magnetic body disposed on an intake/exhaust valve of an
engine is made of an amorphous material, so that a reciprocally
drivable portion including the intake/exhaust valve is rendered
light in weight, thereby allowing the intake/exhaust valve to be
opened and closed under small electromagnetic forces.
According to the present invention, there is provided an
electromagnetic valve actuating system which has a reciprocally
movable magnetic pole in the form of an amorphous body wound as
multiple layers on the intake/exhaust valve. A yoke is provided
having an upper fixed magnetic pole confronting one end of the
movable magnetic pole, an intermediate fixed magnetic pole coupled
to the upper fixed magnetic pole and confronting a side of the
movable magnetic pole, and a distal fixed magnetic pole confronting
the other end of the movable magnetic pole. A upper coil is
provided for generating a magnetic flux passing through the upper
fixed magnetic pole, and a lower coil is provided for generating a
magnetic flux passing through the distal fixed magnetic pole.
The electromagnetic valve actuating system opens and closes the
intake/exhaust valve under attractive forces acting between the
reciprocally movable magnetic pole, and the upper and distal fixed
magnetic poles.
Since the movable member is light in weight, the electromagnetic
valve actuating system may produce a reduced output. Thus, the
electromagnetic valve actuating system may be small in size.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing an electromagnetic valve
actuating system according to an embodiment of the present
invention;
FIGS. 2(a) through 2(c) are diagrams showing the flow of magnetic
lines of force within an electromagnet; and
FIG. 3 is a diagram showing the relationship between the distance
which the valve moves and time.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of the present invention will hereinafter be
described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an actuating system according to
an embodiment of the present invention.
An engine 1 has an output shaft, adjacent to which there is
disposed a rotation sensor 2 for detecting the rotational speed and
phase of the output shaft and converting the detected speed and
phase into a signal. The engine 1 has intake and exhaust ports
which are opened and closed by intake and exhaust valves,
respectively. Of these intake and exhaust valves, the intake valve
will mainly be described below.
An intake valve 9 comprises a highly strong, lightweight valve
which is made of a nonmagnetic material such as ceramic. The intake
valve 9 has a stem axially slidably supported by a valve guide
10.
A valve seat 11 is mounted in the intake port of an intake passage
13. The intake port is closed when the head of the intake valve 9
is closely held against the valve seat 11.
An amorphous magnetic body 4 is connected to the stem end of the
intake valve 9. The amorphous magnetic body 4 comprises a foil of
amorphous material wound around the outer circumferential surface
of the intake valve 9. The amorphous magnetic body 4 is divided
into upper and lower portions with a magnetically permeable plate 6
being interposed therebetween, the plate 6 being made of a magnetic
material.
A flange 7 is mounted on the stem of the intake valve 9. Between
the flange 7 and the valve guide 10, there is disposed a spring 8
for preventing the intake valve 9 from dropping into the engine
cylinder when the engine is not in operation.
An electromagnet 3 is disposed around the amorphous magnetic body
4. The electromagnet 3 has an upper fixed magnetic pole 3a
positioned therein and facing the upper end face of the amorphous
magnetic body 4, an intermediate fixed magnetic pole 3b extending
around and facing the outer circumferential surface of the
amorphous magnetic body 4. The electromagnet 3 also has a distal
fixed magnetic pole 3c disposed in an opening thereof and
confronting the lower end face of the amorphous magnetic body
4.
An upper coil 5a is disposed in the electromagnet 3 between the
upper fixed magnetic pole 3a and the intermediate fixed magnetic
pole 3b, and a lower coil 5b is disposed in the electromagnet 3
between the intermediate fixed magnetic pole 3b and the distal
fixed magnetic pole 3c.
The intermediate fixed magnetic pole 3b and the amorphous magnetic
body 4 are held out of contact with each other, with a small gap
defined therebetween.
The rotation sensor 2, the upper coil 5a, and the lower coil 5b are
electrically connected to an input/output interface 12d which
receives on input signal and transmits output signals in a control
unit 12. The control unit 12 includes, in addition to the
input/output interface 12d which transmits output signals and
receives an input signal, a ROM 12b for storing a program and data,
a CPU 12a for effecting arithmetic operations under the control of
the program stored in the ROM 12b, a RAM 12c for temporarily
storing the input signals and the results of arithmetic operations,
and a control memory 12e for controlling the flow of signals in the
control unit 12.
Operation of the electromagnetic valve actuating system according
to the present invention will be described below.
FIGS. 2(a) through 2(c) show the flow of magnetic lines of force in
the electromagnet 3. FIG. 2(a) shows the flow of magnetic lines of
force when the valve is to be closed. FIG. 2(b) shows the flow of
magnetic lines of force when the valve starts being opened from the
closed condition. FIG. 2(c) shows the flow of magnetic lines of
force when the valve starts to move in a closing direction after
its movement in the opening direction has been decelerated.
In FIG. 2(a), the upper coil 5a is energized with supplied DC
electric energy. Magnetic lines of force generated by the upper
coil 5a pass through a magnetic path which extends from the upper
fixed magnetic pole 3a through the amorphous magnetic body 4 and
then through the intermediate fixed magnetic pole 3b back to the
upper fixed magnetic pole 3a.
When the magnetic lines of force thus flow from the amorphous
magnetic body 4 to the intermediate fixed magnetic pole 3b, the
magnetic lines of force must move across the laminated layers in
the amorphous magnetic body 4. Since the magnetic reluctance across
the laminated layers is larger due to interlayer boundaries, it
obstructs the flow of the magnetic lines of force.
Therefore, the magnetic lines of force which flow in the laminated
layers flow to the magnetically permeable plate 6, and then pass
from the magnetically permeable pate 6 to the intermediate fixed
magnetic pole 3b. In this manner, the magnetic reluctance is
reduced, preventing electromagnetic forces from being lowered.
The flow of the magnetic lines of force produce an N (North) pole
on the upper fixed magnetic pole 3a, and an S (South) pole on the
surface of the amorphous magnetic body 4 which faces the upper
fixed magnetic pole 3a. The upper fixed magnetic pole 3a and the
amorphous magnetic body 4 are attracted to each other.
Immediately before the upper fixed magnetic pole 3a and the
amorphous magnetic body 4 contact each other, the head of the
intake valve 9 is closely held against the valve seat 11, thereby
closing the intake port.
As shown in FIG. 2(b), when the rotational phase of the engine 1 as
detected by the rotation sensor 2 reaches the timing to open the
intake valve 9, the upper coil 5a is de-energized, and the lower
coil 5b is energized.
Magnetic lines of force generated by the lower coil 5b flow through
a magnetic path which extends from the distal fixed magnetic pole
3c to the amorphous magnetic body 4 and then from the amorphous
magnetic body 4 through the magnetically permeable plate 6 and the
intermediate fixed magnetic pole 3b and then back to the distal
fixed magnetic pole 3c.
In the magnetic path described above, an S pole is produced on the
surface of the amorphous magnetic body 4 which faces the distal
fixed magnetic pole 3c and an N pole is produced on the distal
fixed magnetic pole 3c, so that the amorphous magnetic body 4 and
the distal fixed magnetic pole 3c are attracted to each other.
Therefore, the intake valve 9 is subjected to a downward attractive
force, starting to move in the opening direction.
Upon elapse of a first preset time after the intake valve 9 has
started moving in the opening direction, the lower coil 5b is
de-energized and the upper coil 5a is energized again. As with the
condition shown in FIG. 2(a), the intake valve 9 is subjected to an
attractive force in the upward direction, i.e., in the closing
direction. The attractive force serves to decelerate the intake
valve 9 which is moving in the opening direction, and finally stop
the intake valve 9.
FIG. 2(c) shows the condition of the intake valve 9 in the position
in which it is stopped with the valve completely open. This
position corresponds to a position in which it has traversed the
maximum downward stroke.
After the intake valve 9 is stopped, the upper coil 5a is
continuously energized to start moving the intake valve 9 in the
upward direction, i.e., in the closing direction.
After elapse of the first preset period of time and upon elapse of
a second preset time, the upper coil 5a is de-energized and the
lower coil 5b is energized again, applying a downward force to the
intake valve 9. This is to decelerate the intake valve 9 as it
moves in the closing direction, thereby lessening shocks imposed
when the head of the intake valve 9 is seated on the valve seat
11.
After elapse of the second preset period of time and upon elapse of
a third preset time, the lower coil 5b is de-energized and the
upper coil 5a is energized again, so that the magnetic path shown
in FIG. 2(a) is formed, imposing an upward force on the intake
valve 9. The intake valve 9 now closes the intake port, and remains
to close the intake port until next opening timing.
The first, second, and third preset times are determined as
follows: A table of preset times and engine rotational speeds is
stored in advance in the ROM 12b, and a preset time corresponding
to a certain engine rotational speed is determined from the table
based on the rotational speed of the engine 1 detected by the
rotation sensor 2.
The opening and closing condition of the valve will be described
with reference to FIG. 3.
FIG. 3 shows a cam profile curve. The horizontal axis of the graph
indicates the time from the opening timing of the intake valve 9,
and the vertical axis indicates the distance by which the intake
valve 9 moves. The curve in FIG. 3 shows the change, over time, in
the distance by which the intake valve moves.
At a time I which is the valve opening timing, the upper coil 5a is
de-energized and the lower coil 5b is energized to switch the flow
of magnetic lines of force from the condition shown in FIG. 2(a) to
the condition shown in FIG. 2(b). The intake valve 9 is now
subjected to an attractive force in the opening direction, and
starts moving in the opening direction while being accelerated.
At a time II when the first preset time elapses, energization is
switched from the lower coil 5b to the upper coil 5a to switch the
flow of magnetic lines of force from the condition shown in FIG.
2(b) to the condition shown in FIG. 2(c). An attractive force in
the closing direction now acts on the intake valve 9, decelerating
the intake valve 9 as it moves in the opening direction. After the
intake valve 9 has reached the maximum stroke position, the intake
valve 9 reverses its movement for the closing direction.
At a time III when the second preset time elapses, an attractive
force in the opening direction is applied again to the intake valve
9, decelerating the intake valve 9 as it moves in the closing
direction.
At a time IV when the third preset time elapses, the magnetic lines
of force are brought into the condition shown in FIG. 2(a). The
intake valve 9 remains closed until next opening timing.
When the operation of the engine 1 is finished, the upper and lower
coils 5a, 5b are de-energized, and any electromagnetic forces for
holding the intake valve 9 closed are eliminated. Therefore, the
intake valve 9 is maintained in the closed position by the spring
8. The holding force of the spring 8 is sufficiently small with
respect to the attractive force generated by the lower coil 5b to
open the intake valve 9.
The ROM 12 may store, in addition to the table of preset times and
engine rotational speeds, a map of engine rotational speeds and
valve opening timing values. By varying the valve opening timing
depending on the engine rotational speed using the map, the engine
output and efficiency can be increased in a full range of engine
rotational speeds.
Furthermore, an engine cylinder control process for increasing or
reducing the number of engine cylinders that are in operation can
be carried out by actuating or disabling the intake and exhaust
valves associated with the engine cylinders depending on the
rotational speed of the engine 1.
While the intake valve has been described above, the actuating
system of the present invention is also applicable to the exhaust
valve, which is omitted from illustration.
Although a certain preferred embodiment has been shown and
described, it should be understood that the pre sent invention
should not be limited to the illustrated embodiment but many
changes and modifications may be made therein without departing
from the scope of the appended claims.
The electromagnetic valve actuating system according to the present
invention is useful as a system for actuating intake and exhaust
valves of an engine, and suitable for use with an engine which is
required to vary the timing to open and close the intake and
exhaust valves depending on changes in an operating condition such
as the engine rotational speed. Since the amorphous magnetic body
on the valve is lightweight, less power is required by the
electromagnetic system and the system may therefore be small in
size and more efficient to operate.
* * * * *